Facsimile detection system and method

Abstract

In connection with enhanced telephone service, such as personal number service, the detection of whether an incoming telephone call is a facsimile transmission or an ordinary voice call is improved by a utilizing a modified ring back signal during the time in which the service circuit node of the telephone system is attempting to detect the presence of the calling tone (CNG signal) of the sending facsimile machine. Particularly, the ring back signal is modified to increase the off time of the ring back signal to be greater than the period of the CNG signal. Where the CNG signal is a periodic signal with a period of 4 seconds with a 0.5 on time and a 3.5 off time, the modified ring back signal has a period of 7 seconds with a 2 second on time and a 5 second off time.

What is claimed is: 
     
       1. In an advanced intelligent network for a telephone system for routing a call from a calling party's equipment to a called party, wherein prior to completion of the call to the called party, the call from the calling party's equipment is connected via a line to a service circuit node for the purpose of determining whether a CNG signal, having a CNG period consisting of an on time and an off time, is present in the call from the calling party's equipment, the improvement comprising a detector in the service circuit node connected to the line and a file in the service circuit node for generating a modified ring back tone on the line wherein the modified ring back tone has a period with an on time and an off time wherein the off time is greater than the period of the CNG signal. 
     
     
       2. The telephone system of claim 1, wherein the CNG signal as a period of 4 seconds consisting of a 0.5 second tone (on) followed by 3.5 seconds of silence (off) and the file generates a modified ring back tone having a period of 7 seconds consisting of a 2 second tone (on) followed by 5 seconds of silence (off). 
     
     
       3. A method for routing a telephone call in an advance intelligent network, including a service circuit node, comprising the steps of: a. determining whether the call requires identification of calling tone signals (CNG) in an incoming call from a calling party's equipment, wherein the CNG signal has a CNG period consisting of an on time and an off time;   b. upon determining that the call requires identification of CNG tones, routing the call to the service circuit node via a line   c. establishing a connection from the calling party's equipment to the service circuit node;   d. transmitting a modified ring back tone from the service circuit node to the calling party's equipment via the connection, wherein the modified ring back tone has a period consisting of an on time and an off time and wherein the off time of the modified ring back tone is greater than the CNG period;   e. detecting whether the incoming call from the calling party's equipment includes the CNG signal;   f. completing the call to a predetermined destination based on the results of detecting whether the incoming call from the calling party's equipment includes the CNG signal.   
     
     
       4. The method of claim 3, wherein the CNG signal has a period of 4 seconds consisting of a 0.5 second tone (on) followed by 3.5 seconds of silence (off) and the modified ring back tone has a period of 7 seconds consisting of a 2 second tone (on) followed by 5 seconds of silence (off).